Noradrenaline increases hyperalgesia to heat in skin sensitized by capsaicin

Abstract

M skin sensitized by topical application of 0.6% capsaicin was measured at sites of noradrenaline or saline ionophoresis in 10 healthy subjects. At control sites and sites of saline ionophoresis heat hyperalgesia decreased over the course of the experiment as inflammation subsided. In contrast, heat hyperalgesia persisted at sites of noradrenaline ionophoresis. These findings are consistent with neurophysiological observations that noradrenaline and sympathetic neural stimulation increase nociceptor discharge in inflamed skin, and suggest that sympathetic neural activity might increase pain associated with skin damage. ∗Corresponding author: Dr. Peter Drummond, Department of Psychology, Murdoch University, 6150 Western Australia, Australia. Tel.: (61) 9-3602415; FAX: (61) 9-3101899 E-mail: drummond@csuvax1.csu.murdoch.edu.au (Received 31 January 1994; revision received 1 June 1994; accepted 6 June 1994.) © Lippincott-Raven Publishers....